When a character does something that contradicts their previously established beliefs or actions, we often hear that this is a character inconsistency and is an example of bad writing. While there is some truth to this, is it really the case that humans behave in accordance with their beliefs at all times? Is the inconsistency not actually proof that these characters are human, rather than idealised creations representing whatever virtue or vice the writer desires? This isn’t always the case, writers sometimes do write bad and contradictory characters without awareness, but I do think we over-generalise the principle.
The strangest part about this is that writing a character that is too consistent is probably the greater issue. A villain who is simply all bad and has absolutely no good characteristics may be good within certain narratives, but that villain cannot be interesting on an emotional level to the audience, they must simply be a device to impart fear or other emotions, perhaps themes. The internal life of such a character is likely to be rather dull, with very little decision-making.
With this idea in mind, I usually think of inconsistency differently to most. Any interesting or strange character should have what appear as inconsistencies, and indeed, a complex plot may require these inconsistencies or may use them as a focal point for the novel. For instance, why does Ned Stark from GOT decide to betray his belief in honesty being the best policy when it comes to Jon Snow and his parentage? This appears to be an inconsistency, until we realise that Ned has other values alongside honour, loyalty to his family being foremost, and when this conflicts with notions of honour he will often side with his family.
I understand that people will say that Ned is not an inconsistent character once every we understand the conflicts within him and I agree. The major point I am attempting to make is that we should not make swift judgements about a character behaving inconsistently as we may find later that these inconsistencies make sense, or we may never have it explained and have to guess at the motivations of certain characters. To me, this is a legitimate way of writing a story that an intelligent writer can use, and I think it would be a large shame to have the latter technique crushed under standard writing advice, demanding that a character’s every action be clearly explained by their beliefs. We should remain open to the possibility of not quite understanding characters, as both readers and writers.